Study of low work function materials for hot cavity resonance ionization laser ion sources

The selectivity of a hot cavity resonance ionization laser ion source (RILIS) is most often limited by contributions from competing surface ionization of the hot walls of the ionization cavity. In this article we present investigations on the properties of designated high temperature, low work function materials regarding their performance and suitability as cavity material for RILIS. Tungsten test cavities, impregnated with a mixture of barium oxide and strontium oxide (BaOSrO on W), or alternatively gadolinium hexaboride (GdB₆) were studied in comparison to a standard tungsten RILIS cavity as being routinely used for hot cavity laser ionization at ISOLDE. Measurement campaigns took place at the off-line mass separators at ISOLDE/CERN, Geneva and RISIKO/University of Mainz.     

Photochemie von Bis-2H-tetrazolen. III. Nachweis von Bisnitriliminen durch Tieftemperatur-UV-Spektroskopie und thermische Folgereaktionen durch Photolyse von Bis-2H-tetrazolen

Photochemistry of Bis-2H-tetrazoles. III. Detection of Bisnitrilimines through Low-Temperature-UV-Spectroscopy and Thermic Consecutive Reactions through Photolysis of Bis-2H-tetrazoles The photolysis of 2H-tetrazoles ( 1 ) leads to nitrilimines. Bis-2H-tetrazoles form correspondingly bisnitrilimines 2 . They were detected directly by the photolysis of bis-2H-tetrazoles ( 1 ) in an ethanol/ether glass at 95 K. The absorption maxima are depend in an expected manner on the substituents. In the presence of dipolarophiles the reaction of bis-2H-tetrazoles ( 1 ) at room temperature gives bis-Δ²-pyrazolines ( 3 ). These reactions can also be explained by a photoreaction of bis-2H-tetrazoles ( 1 ) to bisnitrilimines 2 at 95 K and subsequent cycloaddition above 150 K. Some bis-Δ²-pyrazolines ( 3 ) are described. The photolyses of bis-2H-tetrazoles ( 1 ) to the bisnitrilimines 2 proceed as one step eliminations of two molecules of nitrogen.     

Field-Emission Cathodes Based on Microchannel Plates

Semiconductors - The existing methods of fabricating low-field cathodes do not permit the development of device structures that comply with the requirements of developers of systems. In this work,...     

Holzeigenschaften von Buchen aus immissionsgeschädigten Beständen

In 48 trees from two immission-damaged beech stands in the Hils, Lower Saxonia, both over 100 years old, the anatomical wood properties at breast height (1,30 m) were investigated. From 24 trees out of each stand 12 trees belonged to damage class 0 and the others to damage class 2. On samples of the annual ring sequence 1975–85 and the undamaged annual ring sequence 1945–1955 fibre length, the water conducting tissue and the percentage of cell species were investigated. No abnormal variations of the anatomical wood properties due to immissions could be found.     

Influence of the zeolite structure and acidity on the hydroisomerization of n-heptane

Different acid solids loaded with 1 wt.% of Pt have been studied in n-heptane hydroisomerization in order to determine the influence of porosity and acidity (considered measured by the activity) on selectivities. The open solids like Y and β zeolites and a pillared clay present different activities towards n-C₇ conversion but similar selectivities. Consequently, acidity seems to be a less important parameter in n-C₇ isomerization than porosity. Very different results were obtained as a function of the solid structure and so n-heptane hydroconversion appears to be a simple and rapid method to obtain data concerning the porosity of unknown zeolite structures. The highest content of multibranched isomers was obtained on open solids but the value predicted by the thermodynamic was never reached due to the fact that cracking of multibranched isomers is initiated quickly.     

Effect of a mixture of steam-flaked corn and soybeans on health, growth, and selected blood metabolism of Holstein calves

The objective of the experiment was to evaluate the effects of steam-flaked corn grains and soybeans on calf health, growth, and selected blood parameters. Holstein bull calves (n = 30, approximately 7 ± 3 d of age) were purchased from local dairy farms and offered milk, starter diets, and hay, and were then assigned to the experiment at 21 ± 3 d of age. Calves were blocked into 3 treatments by birth date and body weight and randomly assigned to receive fresh milk and a commercial pelleted starter containing extruded corn and soybeans (ECS), steam-flaked corn and soybeans (SFCS), or ground corn and soybeans (GCS). The experiment was conducted with calves from 3 to 13 wk of age. Body weight, calf starter intake, milk intake, total dry matter intake, and body structural growth were not significantly influenced by corn and soybean processing during the study; however, feed efficiency was significantly improved by the SFCS treatment. Average daily gain generally decreased during the weaning week for all treatments, but did not differ significantly among treatments. Health incidences for calves fed the SFCS starter were lower than those fed the other 2 treatments. The blood hematocrit was higher for calves fed the SFCS starter than for those fed the GCS and ECS starters during wk 6 to 11. The concentration of plasma β-hydroxybutyrate was higher for the calves fed the GCS and SFCS treatments than for those fed the ECS treatment during wk 6 to 13, but lower during wk 4 and 5. Plasma glucose concentrations decreased remarkably with increasing calf age but were not affected by corn and soybean processing. Plasma nonesterified fatty acids were influenced by calf age, and higher NEFA concentration was observed in the SFCS treatment than in the other 2 treatments during wk 5 to 9. Calves consuming the SFCS starter had similar average daily gain, milk intake, starter intake, total dry matter intake, and body structure, but had improved feed efficiency when compared with animals consuming the GCS and ECS starters. The SFCS starter decreased incidence of diarrhea during the postweaning period and required less veterinary treatment. These data suggest that the steam-flaking of corn and soybeans can influence the growth performance and the selected blood parameters of calves and that, in this study, the extrusion of corn and soybeans had no beneficial effect on the growth performance of calves.